Safety device for two-stroke cycle gas engines



L. PRECHTEL Feb. 23, 1932.

SAFETY DEVICE FOR TWO-STROKE CYCLE GAS ENGINES Fiied nob. so. 1928 2 Sheets-Sheet Fig. 4

Feb. 23, 1932.

SAFETY DEVICE FOR TWO-STROKE CYCLE GAS ENGINES Filed Nov. 30, 1928 V 2 Sheets-Sheet 2 Fig.3

R ugug- L. PRECHTEL 1,846,654 I Patented Feb. 23, 1932 UNITED STATES PATENT OFFICE LUDWIG PRECHTEL, OF NUREMBERG, GERMANY, ASSIGNOR TO MASCHINENFABRIK AUGSBURG-NURNBEBG A.-G., 0F NUREMBERG, GERMANY, A CORPORATION OF GERMANY SAFETY DEVICE FOR TWO-STROKE CYCLE GAS ENGINES Application filed' November 30, 1928, Serial No.322,596, and in Germany December 15, 1927.

Heretofore it has been usual with two stroke cycle gas engines to supply the proper quantities of gas and air to the working cylinder by reciprocating or piston blowers which are directly driven by the gasengine. In this case the valves of said blowers which are always .to be found thereon are provided to prevent any communication which during the stopping of the engine may exist between the gas and air conduits. Blowers driven in this manner by gas engines as well as the auxiliary apparatus connected with such blowers are not suitable in case of high speed two stroke cycle gas engines in frequent use at the present time, this being due to the high speed at which the blower necessarily operates in such a case. Instead of the blower being driven directlyby the gas engine, the blower may. be driven independently, as for instance by an electric motor, turbine-blowers being especially suitable for this purpose, Turbine-blowers, however, have no automatic valves such as are necessarily employed in connection with reciprocating blowers, and in case the gas engine for some reason comes to a stop, it may happen that the blower will continue to operate and cause in certain positions of the working piston the cylinder of the gas engine or also the exhaust pipe to be filled with a combustible mixture. Also the gas or air conduit will be filled with a combustible mixture, if the gas and air pressures prevailing therein are not quite even. This combustible mixture may ignite at some hotpoint of the engine, for instance, at the exhaust and cause injuries-to persons or machinery. For these reasons heretofore the greatest possible care and attention as well as great presence of mindon the part of the attendant-was necessary in order to prevent accidents.

My invention has for its principal object to positively avoid this source of danger and to provide a safety device which Wlll protect automatically and independently from any manual operation the engine as well as the attendant or other persons which may come in contact with the engine.

The object in view I attain according to my invention by providing a closing valve in either purely mechanical means may be used as controlling organs or also a controlling liquid, such as employed in connection with systems of control, in which pressure-oil is used as the controlling agent.

In the accompanying drawings in which have represented some embodiments of the novel safety device according to my invention and the mode of controlling said device from the engine, Fig. 1 is a side-view of a two stroke cycle gas engine provided with a safety device which operates in a purely mechanical way, Fig. 2 a top-view showing some of the parts of said safety device in detail, Fig. 3 a side view of a gas engine similar to Fig. 1 provided with another type of safety device operating on the principles of a pressure oil control system. and acting to properly con- 1 trol the gas closing valve of the engine, the reversingorgan forthe pressure oil being shown in section, Fig. 4 is a section through said reversing organ after completed reversal thereof. According to Fig. 1 the sleeve 1 of-the engine governor actuates a bell-crank lever 2, the free arm of said lever being connected to one end of an actuating rod 3. The other end of said rod 3 has pivoted thereto an angularly shaped pawl 4 of a spring 5 in the 'position' as shown which position corresponds to the normal speed of the engine. An extension 6 of said pawl 4 in the position shown contacts with said rod 3. An angularly shaped extension 7 of the bell-crank-lever 8 projects into the range of action of the upwardly directed arm of said pawl 4, said bell-crank-lever 8 being kept in its normal position by means of a spring 9, in which position the downwardly directed arm of said. lever 8 engages with a fixed which is kept by means 35 'gine speeds up,

13 which lower end projects from the valvecasing 12, an extension 15 of the bell-crank lever engaging with said finger 14 in the open position of the valve 11, so that the latter will be kept open against the action of the spring 16 which tends to close the valve. The upper end of the valve-rod 13 which upper end projects from the valve-casing 12 is provided with a handle 17. The horizontally directed arm 4a of the pawl 4 extends into the range of action of the finger 14 which is of relatively great width.

In order to open the valve 11 when starting the engine, the valve-rod 13 is pushed downward by the aid of the handle 17, the sleeve 1 of the governor being at this time in its lower-most position and accordingly the rod 3 as well as the pawl 4 in their topmost position, so that the pawl 4 will keep the bellcrank lever 8 swung towards the right-hand side. The finger 14 on the valve-rod 13 therefore will be able to move past the extension 15 of the bell-crank lever 8, although the finger 14 could not be kept in fixed position by said extension 15, due to the pressure exerted upon the handle 17 being released. In order, therefore, to facilitate engagement of the bell-crank lever 8 or of the extension 15 on the latter, the stroke'of the valve-rod 13 is so proportioned that upon depression of the same the finger 14 will come in engagement with the arm 4a of the pawl 4, thus causing the latter to swing outwardly as indicated by the arrow shown in Fig. 1. At the same time the vertically positioned arm of the pawl 4 which engages from below with the horizontal arm 7 of the bell-crank lever 8 will become disengaged from said arm 7 and being moved into normal position by the spring 5, said bell crank-lever now engaging with the stop 10, while the extension 15 of the bell-crank lever 8 will lock the return way for the finger 14 on the valve rod 13. The finger 14, therefore, during the releasing of the handle 17 engages with the extension 15 of the bell-crank lever 8 so that the valve remains in open position permitting the starting of the engine. The vertically positioned arm of the pawl 4 which in the meanwhile had been carried back by action of the spring 5 at first engages with the arm 7 of the bellcrank lever 8 and moves back into its normal position underneath said arm 7 during the upward motion of the sleeve 1 of the governor motion is due to the fact that the enand during the consequent downward motion of the rod 3. If now, for some reason the engine comes to a stop, the vertically positioned arm of the pawl 4 will which again cause the bell-crank lever 8 to swing outwardly, so that the extension 15 of the said lever will slide oil the finger 14 thus causing the valve 11 to suddenly close due to the action of the spring 16.

Preferably the arrangement of the several controlling organs is so made that the valve 11 will also be closed in case the speed of the engine is in excess of the permissible speed. For this purpose therod 3 is provided with an arm 18, which by way of the double-armed swinging lever 19 will cause the bell-crank lever 8 to swing towards the outside, if the rod 3 has been moved downward after the sleeve 1 of the engine governor has assumed its uppermost position. The valve 11 therefore will also be closed automatically, if the speed of the engine has increased above normal.

According to Fig. 3 thewvalve 11 is kept in open condition against the action of the spring 20 by means of pressure-oil which is taken out of the oil container 21 by the pump 22 and is supplied through the pipe 23 and the main channel 24 of three-way valve 25 to the cylinder 26 with the piston 27 which is connected to the valve-rod. The threeway valve 25 is associated with a discharge conduit 28, which may be connected in the manner hereinbelow described with the oil conduit leading to the cylinder 26 by way of the main channel 24 of the three-way valve 25 and the channel 29 thereof. A doublearmed lever 30 is connected to the cock of the three-way valve 25 one arm of said lever 30 being weighted and the other arm being constructed in the shape of a finger similar to the finger 14 shown in Fig. 1. An extension 15 of a bell-crank lever 8 again co-operates with said finger 14, said extension 15 being arranged similarly to the extension 15 on the bell-crank lever 8 of Fig. 1. In like manner the bell-brank lever 8 together with the extension 15 thereon is operated by intermediate members from the sleeve 1 of governor. In order to start the engine, the cock of the three-way valve 25 is brought into the positon shown in Fig. 3 by lifting the weight on the lever 30, the horizontal arm of the pawl 4 being now again caused to swing outwardly by action of the finger 14, so that the extension 15 on the bell-crank lever 8 will move into the return-way of the finger 14. In consequnce thereof the connection between the oil-pump 22 and the cylinder 26 will remain established through the main-channel of the three-way valve 25 so that the engine may be started. If the engine for some reason should come to astop, the rod 3 or the pawl 4 will cause the bell-crank lever to swing outward, this causing the extension 15 on the bell-crank lever 8 to slide oif the finger 14, thus reversing the valve 25 under the action of the one-sided weight on the lever 30, to come into the position shown in Fig. 4. The connection between the oil-pump 22 and the cylinder 26 will now be interrupted, while a connection is established between the cylinder 26 and the oil container 21 by way of the channel 29 so that the piston 27 by action of the spring 20 may press the oil out of the cylinder 26, whereupon the valve 11 again be immediately closed.

In this case also the arm 18 which is provided laterally on the rod 3 together with the double-armed lever 19 will close the valve 11 if the speed of the engine rises above normal.

I claim:

1. In an internal combustion engine inclusive of a fuel inlet conduit, a valve for controlling the flow of fuel through said conduit, means constantly tending to move said valve to a position closing said conduit, releasable mechanical holding means for maintaining said valve in an open position during normal operation of the engine within predetermined high and low rates of speed, and mechanical means rendered effective by stopping of the engine to release said valve holding means.

2. In an internal combustion engine in- I will 'clusive of a fuel inlet conduit, a valve for controlling the flow of fuel through said conduit, means constantly tending to movesaid valve to a position closing said conduit, releasable holding means for maintaining said valve in an open position during normal operation of the engine within'predetermined high and low rates of speed, and means rendered effective by the speed of the engine eiiceeding a predetermined rate to release said valve holding means.

3. In an internal combustion engine inelusive 'of a fuel inlet conduit and a valve for controlling said conduit, means constantly tending to move said valve to a position closing said conduit, releasable. means for holding said valve open during normal operation of the engine within predetermined rates of speed, and means rendered effective by the speed of operation of the engine either exceeding or falling below the predetermined normal high and low rates of speed thereof to release said valve holding means.

4. In an internal combustion engine inclusive of a fuel inlet conduit and avalve for controlling said conduit, releasable holding means for maintaining said valve open during normal operation of the engine within predetermined high and low rates of speed, means rendered effective by the speed of the engine falling below a predetermined low rate to release said holding means, and

means operable immediately upon release of said holding means to close sald'valve.

5. In an internal combustion engine inclusive of a fuel inlet conduit and a' valve for controlling said conduit, releasable holding means for maintaining said valve open duringn'ormal operation of the engine within predetermined high and low rates of speed, means rendered effective by the speed of the engine exceeding a predetermined high rate to release said holding means, and means operable immediately upon release ,of said holding means to close sald valve.

6. In an internal combustion engine inly tending to move said valve to a position closing said conduit, a pivoted latch member for maintaining said valve in an open position during normal operation of the engine within predetermined high and low rates of peed, an engine operated governor, and means operated by said governor to effect pivotal movementof said latch member to release said valve upon the speed of the engine falling below or exceeding the predetermined normal high and low rates of speed thereof.

7. In an internal'combustion engine inelusive of a fuel inlet conduit and a valve for controlling said conduit, means constantly tending to move said valve to a position closing said conduit, apivoted latch member for maintaining said valve in an open position during normal operation of the engine within predetermined high and low rates of speed, an engine operated governor, a rod 'reci roeal b said overnor and means whereby movement of said rod beyond a redetermined point in either direction e ects pivotal movement of said latch member to release said valve.

8.2In an internal combustion engine inclusive of a fuel'inlet conduit and a valve for controlling said conduit,-means constantly tending to move said valve to a position closing said conduit, fluid pressure holding means for maintaining said valve open during normal operation of the engine within predetermined highand low rates of speed, and means rendered eflective by the speed of the engine falling below a predetermined low rate to release said fluid pressure holding means.

. 9. in an internal combustion engine in-- clusive of a fuel inlet conduit and a valve clusive of a fuel inlet conduit and a valve for controlling said conduit, means constantly tending to move said valve to a position closing said conduit, :1. cylinder, a piston within said cylinder in controlling relation to said valve, a fluid supply pipe connected with said cylinder, means for supplying fluid under pressure through said pipe to said cylinder and against said piston to maintain said valve open during operation of the engine within predetermined high and low rates of speed thereof, a fluid control valve interposed in said ipe movable between a position to permit ow of fluid to said cylinder and a position to out off such flow and to vent the cylinder, means for holding said fluid control valve in the aforesaid first mentioned position during operation of the engine within the predetermined normal high and low rates of speed thereof, means rendered effective by the speed of the engine falling below the predetermined normal low rate of speed thereof to release said holding means, and means operable immediately upon release of said holding means to move said fluid control valve to its aforesaid second mentioned position.

11. In an internal combustion engine inelusive of a fuel inlet conduit and a valve for controlling said conduit, means constantly tending to move said valve to a position closing said conduit. a cylinder, a piston within said cylinder in controlling relation to said valve, :1 fluid supply pipe connected with said cylinder, means for supplying fluid under pressure through said pipe to said cylinder and against said piston to maintain said valve open during operation of the engine within predetermined high and low rates of speed thereof, a fluid control valve interposed in said pipe movable between a position to permit flow of fluid to said cylinder and a position to cut off such flow and to vent the cylinder, means for holding said fluid control valve in the aforesaid first mentioned osition during operation of the engine wlthin the predetermined normal high and low rates of speed thereof, means rendered effective by the speed of the engine exceeding a predetermined high rate to release said holding means, and means operable immediately upon release of said holding means to move said fluid control valve to its aforesaid second mentioned position.

LUDWIG PRECHTEL. 

